java - 我该如何阻止这个整数溢出？

Question

好吧，所以我遇到了这个问题，您可能会出现错误，从而获得比实际支付的更多的东西。这有点难以解释，当你增加数量时，首先这是我的代码:

    public void setAmount(Player player, int button) {
        int amount = (Integer) player.getTemporaryAttribute("geAmount");
        int id = (Integer) player.getTemporaryAttribute("geItem");
        int price = (Integer) player.getTemporaryAttribute("price");
        long totalPrice = price * amount;
        switch(button) {
        case 157:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            if(amount > 1) {
                amount--;
            } else {
                amount = 1;
            }
            break;
        case 159:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            if(amount < Integer.MAX_VALUE && totalPrice <= Integer.MAX_VALUE && totalPrice >= 0) {
                amount++;
            }
            break;
        case 162:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            if(player.getTemporaryAttribute("buying") == Boolean.TRUE && totalPrice <= Integer.MAX_VALUE && totalPrice >= 0) {
                amount += 1;
            } else {
                amount = 1;
            }
            break;
        case 164:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            if(player.getTemporaryAttribute("buying") == Boolean.TRUE && totalPrice <= Integer.MAX_VALUE && totalPrice >= 0) {
                amount += 10;
            } else {
                amount = 10;
            }
            break;
        case 166:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            if(player.getTemporaryAttribute("buying") == Boolean.TRUE && totalPrice <= Integer.MAX_VALUE && totalPrice >= 0) {
                amount += 100;
            } else {
                amount = 100;
            }
            break;
        case 168:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            if(player.getTemporaryAttribute("buying") == Boolean.TRUE && totalPrice <= Integer.MAX_VALUE && totalPrice >= 0) {
                amount += 1000;
            } else {
                amount = player.getInventory().getContainer().getNumberOff(id);
            }
            break;
        case 171:
        case 173:
            if(player.getRights() > 1){
                player.sm(""+totalPrice+"");
            }
            player.getActionSender().sendConfig(1111, (Integer) player.getTemporaryAttribute("price"));
            break;
        }
        if(amount == 0){
            amount = 1;
        }
        if(amount >= Integer.MAX_VALUE || amount < 0) {
            amount = Integer.MAX_VALUE;
        }
        player.setTemporaryAttribute("geAmount", amount);
        player.getActionSender().sendConfig(1109, id);  
        player.getActionSender().sendConfig(1110, amount);
    }

总价一直在溢出，但我不知道如何让它停止。有人建议使用这样的东西:

int last = 0;
int current = 0;
while(last < current) //loop terminates on overflow
  last = current++;

但我不知道如何在这段代码中使用它。有人可以帮我吗？

Answer 1

使用BigInteger类

http://docs.oracle.com/javase/1.5.0/docs/api/java/math/BigInteger.html